The present invention relates to an electronic musical instrument and, more particularly, to an electronic musical instrument with a sequencer for automatic arpeggio performance.
It is very difficult for beginners to play arpeggio or broken chord, i.e. play the notes of a chord in quick succession instead of simultaneously. It is desired, therefore, that an electronic musical instrument be provided with a sequencer enabling the arpeggio or broken chord to be automatically played.
FIG. 1 shows a basic construction of a conventional electronic musical instrument incorporated with such a sequencer. In FIG. 1, reference numeral 11 is a frequency-variable clock pulse generator for generating clock pulses with a frequency corresponding to the tempo of a musical composition being performed. The output clock pulse of the clock pulse generator 11 is applied to a sequential pulse generator 12 to which a start/stop control switch 13 is operatively coupled, and causes the pulse generator 12 being enabled by the switch 13 to produce sequentially and circulatingly output pulses at the outputs thereof. The output pulses of the sequential pulse generator 12 are applied to the control inputs of a plurality of gates 14, respectively. A pitch voltage setting circuit 15 including a plurality of potentiometers connected across a DC power source applies a plurality of pitch voltage signals (referred to as MV signals) memorized (prepared) in the pitch voltage setting circuit 15 to the inputs of the gates 14. Upon receipt of the output pulses from the sequential pulse generating circuit 12, the gates 14 are sequentially and circulatingly enabled to allow the memorized MV signals to be read out sequentially (usually one after another) and repeatedly on commonly connected outputs of the gates 14. The MV signals in serial form from the gates 14 are applied to a voltage-controlled frequency-variable oscillator (hereinafter referred to as VCO) 16. The VCO 16 sequentially produces tone signals with frequencies corresponding to the magnitudes (D.C. voltage values) of the MV signals. The tone signals from the VCO 16 are in turn applied to a voltage-controlled cutoff-frequency-variable filter (hereinafter referred to as VCF) 17 and a voltage-controlled gain-variable amplifier (hereinafter referred to as VCA) 18. Control waveform generators (CWG) 21 and 22, which are triggered by the clock pulses to produce time-varying control waveform signals, are connected to VCF 17 and VCA 18, respectively, and controls the tone color and amplitude envelope of a tone signal being produced in accordance with the shapes of the time-varying control waveform signals. The musical tone signals from VCA 19 are applied to a sound system including an amplifier 19 and a loudspeaker 20 to sequentially sound tones as memorized in the pitch voltage setting circuit 15.
In the above-mentioned apparatus, the MV signals set in the pitch voltage setting circuit 15 are sequentially applied to the VCO 16 through the gates 14 so that arpeggio, broken chord or the like is automatically performed. Although very similar, the distinction between arpeggio and broken chord depends on pitch voltage setting states in the pitch voltage setting circuit 15, so to speak. In other words, the distinction depends on the notes of tones to be stored in the pitch voltage setting circuit 15 and the order of read-out of the tones stored, i.e. a note pattern memorized. The note pattern is set by a player. The tempo in the performance of the arpeggio or broken chord is adjustable by changing the oscillating frequency of the clock pulse generator 11.
The automatic performance of the arpeggio or broken chord is intended to accompany a keyboard performance by a player; however, the circuits relating to the keyboard performance are omitted in FIG. 1. In the above-mentioned sequencer, the pitch voltages memorized in the pitch voltage setting circuit 15 are fixed. For this reason, it is impossible to change the pitches of the tones to be automatically played during the performance of a musical composition. Therefore, the application of the sequencer is restricted to a specific use.
In the apparatus in FIG. 1, it is necessary to set pitch voltage in the pitch voltage setting circuit prior to a performance. Accordingly, the apparatus is provided with a manual advance switch (not shown) for manually advancing, step by step, the sequential pulse generator. However, provision of the start/stop control switch and the manual advance switch on the control panel of an electronic musical instrument results in complexity of the panel face and high cost.